The present invention relates to sheets that electrostatically adhere to substrates. More specifically, the present invention relates to sheets that adhere to substrates using a combination of electrostatic charge and an additional adhesive.
Films have been provided with electrostatic charges, so that they will adhere to substrates without the use of adhesives. Films having persistent dielectric polarization are called electrets.
U.S. Pat. No. 5,258,214 discloses a preprinted thin plastic film wall covering having a preprinted image thereon and provided with a static electrical charge for securing the coverings to a surface.
U.S. Pat. No. 5,207,581 discloses a writing apparatus including electret film. The electret film, a flexible plastic film having a static electrical charge induced thereto, is capable of being erasably written upon with dry erase markers, as a writing medium. An apparatus is described for holding a roll of electret film.
U.S. Pat. No. 5,989,685 discloses an electret film composition adapted for printing on inkjet printers. This description provides an xe2x80x9cimproved printing material that incorporates the advantages of electrets (sic)xe2x80x9d at column 2, lines 37-39. The advantages of electrets are stated at column 1, lines 53-55 to hold xe2x80x9cthe promise of providing a display which sticks to a surface without the use of fasteners or adhesives.xe2x80x9d The charged sheets of this invention are attached to a paper backing to avoid problems with handling of the sheets in the paper feed mechanisms of printers. These carrier backing papers are adhered to the sheets with a glued edge. Column 4, lines 24-52.
U.S. Pat. No. 5,807,624 discloses an electrostatically charged imaging manifold. The preferred imaging manifolds xe2x80x9ccomprise a transparent, polymeric sheet imageable in an imaging sheet, and attached thereto, an opaque member underlying and in register with said transparent sheet, said opaque member being adhered to said transparent polymeric sheet by means of the combination of an electrostatic charge and a pressure-sensitive adhesive.xe2x80x9d Column 3, lines 55-60. This adhesive is provided to provide additional protection against xe2x80x9cscrunch,xe2x80x9d or to improve feeding performance of the sheet with the carrier paper. See column 12, line 66- column 13, line 2.
U.S. Pat. No. 6,023,870 describes an apparatus for displaying and replacing graphic sheet on vending machines, wherein graphics sheets are removably adhered to the reverse side of the clear display panel by static cling. An alternative embodiment is disclosed at column 7, lines 38-50, which describes the use of partial adhesive or reusable adhesive, defined as a xe2x80x9ctackyxe2x80x9d adhesive, for the removable adhering function. The adhesive described therein is the adhesive that is used on Post-it(copyright) brand notes from 3M, and particularly illustrating the tacky adhesive as SPRAY MOUNT(copyright) artist""s adhesive from 3M, commercially available consumer applicable adhesive that can be applied on location. The specification further states that the principles of the various embodiments can be combined at Column 8, lines 32-36, giving the example that a tacky adhesive may secure the corners of a product graphics sheet that has been initially positioned using the method pertaining to static cling.
The present invention provides a graphic sheet comprising a film having a top and bottom surface. The film has an electrostatic charge and additionally contains a preapplied activatable adhesive. The electrostatic charge is sufficient to support the sheet on a vertical clean insulated surface. The activatable adhesive is capable of assisting in adhesion of the sheet to a display substrate.